The streaming media service is a new service rapidly developed in recent years and transmits multimedia content data such as video and audio data over a packet switching network with the streaming transmission technology. The principal feature of the streaming transmission technology lies in that continuous video and audio data is placed on a website server after processing, thus a user can watch and listen while downloading, instead of watching and listening after downloading the entire file to a used user terminal.
An internet protocol television (IPTV) service is a typical service in the streaming field. As shown in FIG. 1, the current IPTV network architecture mainly includes:
an operation support system configured to provide functions such as charging, authentication, content management and digital right management;
a service application layer configured to provide preprocessing such as content coding/decoding conversion, compression and encryption, user's service management, generation and downloading of electronic program guide, and network portal and application functions such as Video on Demand (VOD), Television (TV) and advertisement.
[A content/media distribution network includes a central media server (CS), an edge media server (ES) and a server providing media scheduling and distribution control. The content/media distribution network is configured to distribute content resources to an edge media server required by a user to alleviate loads of the streaming media service on network.
A forwarding layer is configured to forward streaming media service flow, request support for multicasting, and provide quality of service (QoS) guarantee.
Although the IPTV network architecture shown in FIG. 1 may implement the streaming media service, because this architecture is an independent service system, it cannot share support systems such as user management, authentication, and charging with other service networks, hence increasing operating cost of carriers.
To meet the increasingly prominent common requirement for IP multimedia applications, the Third Generation Partnership Project (3GPP) introduces an IP Multimedia Subsystem (IMS) of pure IP service network architecture based on the packet forwarding network. The IMS uses packet domain as the forwarding channel for upper layer control signaling and media transmission, introduces a session initiation protocol (SIP) as a service control protocol, utilizes the characteristics of simplicity, ease of extension, convenience in media combination of SIP, and provides rich multimedia services by separating service control and forwarding control.
As shown in FIG. 2, the IMS network architecture includes: P/I/S-CSCF, i.e. call status control function entity, configured to provide relevant functions in the IMS network architecture such as subscriber broker, session control, routing, triggering of services and communication between different IMS domains; MGCF/T-MGF, i.e., media gateway control function, media gateway function and signaling gateway function, configured to implement communication between users in the IMS network architecture and those in traditional Public Switching Telephone Network (PSTN); Bleeding-off gateway control function (BGCF) configured to address and route between MGCFs of different IMS domains; SLF configured to implement choice among a plurality of user profile server function (UPSF); IBCF and I-BGF as function entities for communication between IMS domains; MRF, i.e. media resource function, configured to implement allocation, control and processing on media resources, including media resource function controller (MRFC) and media resource function processor (MRFP); Network attachment subsystem configured to implement access authentication and address assignment for users; Resource access control system configured to control forwarding network according to requirements of service layer such as IMS.
Although the IMS network architecture can share support systems, such as user management, authentication, and charging subsystems with other service networks, at present, the IMS network architecture can only effectively support session services and doesn't have functions necessary to implement streaming media services, such as content management, content protection, and electronic program guide delivery, hence current IMS network architecture can not support streaming media services.